phpman > perldoc > IO::Compress::RawDeflate

NAME
    IO::Compress::RawDeflate - Write RFC 1951 files/buffers

SYNOPSIS
        use IO::Compress::RawDeflate qw(rawdeflate $RawDeflateError) ;

        my $status = rawdeflate $input => $output [,OPTS]
            or die "rawdeflate failed: $RawDeflateError\n";

        my $z = IO::Compress::RawDeflate->new( $output [,OPTS] )
            or die "rawdeflate failed: $RawDeflateError\n";

        $z->print($string);
        $z->printf($format, $string);
        $z->write($string);
        $z->syswrite($string [, $length, $offset]);
        $z->flush();
        $z->tell();
        $z->eof();
        $z->seek($position, $whence);
        $z->binmode();
        $z->fileno();
        $z->opened();
        $z->autoflush();
        $z->input_line_number();
        $z->newStream( [OPTS] );

        $z->deflateParams();

        $z->close() ;

        $RawDeflateError ;

        # IO::File mode

        print $z $string;
        printf $z $format, $string;
        tell $z
        eof $z
        seek $z, $position, $whence
        binmode $z
        fileno $z
        close $z ;

DESCRIPTION
    This module provides a Perl interface that allows writing compressed data to files or buffer as
    defined in RFC 1951.

    Note that RFC 1951 data is not a good choice of compression format to use in isolation,
    especially if you want to auto-detect it.

    For reading RFC 1951 files/buffers, see the companion module IO::Uncompress::RawInflate.

Functional Interface
    A top-level function, "rawdeflate", is provided to carry out "one-shot" compression between
    buffers and/or files. For finer control over the compression process, see the "OO Interface"
    section.

        use IO::Compress::RawDeflate qw(rawdeflate $RawDeflateError) ;

        rawdeflate $input_filename_or_reference => $output_filename_or_reference [,OPTS]
            or die "rawdeflate failed: $RawDeflateError\n";

    The functional interface needs Perl5.005 or better.

  rawdeflate $input_filename_or_reference => $output_filename_or_reference [, OPTS]
    "rawdeflate" expects at least two parameters, $input_filename_or_reference and
    $output_filename_or_reference and zero or more optional parameters (see "Optional Parameters")

   The $input_filename_or_reference parameter
    The parameter, $input_filename_or_reference, is used to define the source of the uncompressed
    data.

    It can take one of the following forms:

    A filename
         If the $input_filename_or_reference parameter is a simple scalar, it is assumed to be a
         filename. This file will be opened for reading and the input data will be read from it.

    A filehandle
         If the $input_filename_or_reference parameter is a filehandle, the input data will be read
         from it. The string '-' can be used as an alias for standard input.

    A scalar reference
         If $input_filename_or_reference is a scalar reference, the input data will be read from
         $$input_filename_or_reference.

    An array reference
         If $input_filename_or_reference is an array reference, each element in the array must be a
         filename.

         The input data will be read from each file in turn.

         The complete array will be walked to ensure that it only contains valid filenames before
         any data is compressed.

    An Input FileGlob string
         If $input_filename_or_reference is a string that is delimited by the characters "<" and ">"
         "rawdeflate" will assume that it is an *input fileglob string*. The input is the list of
         files that match the fileglob.

         See File::GlobMapper for more details.

    If the $input_filename_or_reference parameter is any other type, "undef" will be returned.

   The $output_filename_or_reference parameter
    The parameter $output_filename_or_reference is used to control the destination of the compressed
    data. This parameter can take one of these forms.

    A filename
         If the $output_filename_or_reference parameter is a simple scalar, it is assumed to be a
         filename. This file will be opened for writing and the compressed data will be written to
         it.

    A filehandle
         If the $output_filename_or_reference parameter is a filehandle, the compressed data will be
         written to it. The string '-' can be used as an alias for standard output.

    A scalar reference
         If $output_filename_or_reference is a scalar reference, the compressed data will be stored
         in $$output_filename_or_reference.

    An Array Reference
         If $output_filename_or_reference is an array reference, the compressed data will be pushed
         onto the array.

    An Output FileGlob
         If $output_filename_or_reference is a string that is delimited by the characters "<" and
         ">" "rawdeflate" will assume that it is an *output fileglob string*. The output is the list
         of files that match the fileglob.

         When $output_filename_or_reference is an fileglob string, $input_filename_or_reference must
         also be a fileglob string. Anything else is an error.

         See File::GlobMapper for more details.

    If the $output_filename_or_reference parameter is any other type, "undef" will be returned.

  Notes
    When $input_filename_or_reference maps to multiple files/buffers and
    $output_filename_or_reference is a single file/buffer the input files/buffers will be stored in
    $output_filename_or_reference as a concatenated series of compressed data streams.

  Optional Parameters
    The optional parameters for the one-shot function "rawdeflate" are (for the most part) identical
    to those used with the OO interface defined in the "Constructor Options" section. The exceptions
    are listed below

    "AutoClose => 0|1"
         This option applies to any input or output data streams to "rawdeflate" that are
         filehandles.

         If "AutoClose" is specified, and the value is true, it will result in all input and/or
         output filehandles being closed once "rawdeflate" has completed.

         This parameter defaults to 0.

    "BinModeIn => 0|1"
         This option is now a no-op. All files will be read in binmode.

    "Append => 0|1"
         The behaviour of this option is dependent on the type of output data stream.

         *    A Buffer

              If "Append" is enabled, all compressed data will be append to the end of the output
              buffer. Otherwise the output buffer will be cleared before any compressed data is
              written to it.

         *    A Filename

              If "Append" is enabled, the file will be opened in append mode. Otherwise the contents
              of the file, if any, will be truncated before any compressed data is written to it.

         *    A Filehandle

              If "Append" is enabled, the filehandle will be positioned to the end of the file via a
              call to "seek" before any compressed data is written to it. Otherwise the file pointer
              will not be moved.

         When "Append" is specified, and set to true, it will *append* all compressed data to the
         output data stream.

         So when the output is a filehandle it will carry out a seek to the eof before writing any
         compressed data. If the output is a filename, it will be opened for appending. If the
         output is a buffer, all compressed data will be appended to the existing buffer.

         Conversely when "Append" is not specified, or it is present and is set to false, it will
         operate as follows.

         When the output is a filename, it will truncate the contents of the file before writing any
         compressed data. If the output is a filehandle its position will not be changed. If the
         output is a buffer, it will be wiped before any compressed data is output.

         Defaults to 0.

  Examples
    Here are a few example that show the capabilities of the module.

   Streaming
    This very simple command line example demonstrates the streaming capabilities of the module. The
    code reads data from STDIN, compresses it, and writes the compressed data to STDOUT.

        $ echo hello world | perl -MIO::Compress::RawDeflate=rawdeflate -e 'rawdeflate \*STDIN => \*STDOUT' >output.1951

    The special filename "-" can be used as a standin for both "\*STDIN" and "\*STDOUT", so the
    above can be rewritten as

        $ echo hello world | perl -MIO::Compress::RawDeflate=rawdeflate -e 'rawdeflate "-" => "-"' >output.1951

   Compressing a file from the filesystem
    To read the contents of the file "file1.txt" and write the compressed data to the file
    "file1.txt.1951".

        use strict ;
        use warnings ;
        use IO::Compress::RawDeflate qw(rawdeflate $RawDeflateError) ;

        my $input = "file1.txt";
        rawdeflate $input => "$input.1951"
            or die "rawdeflate failed: $RawDeflateError\n";

   Reading from a Filehandle and writing to an in-memory buffer
    To read from an existing Perl filehandle, $input, and write the compressed data to a buffer,
    $buffer.

        use strict ;
        use warnings ;
        use IO::Compress::RawDeflate qw(rawdeflate $RawDeflateError) ;
        use IO::File ;

        my $input = IO::File->new( "<file1.txt" )
            or die "Cannot open 'file1.txt': $!\n" ;
        my $buffer ;
        rawdeflate $input => \$buffer
            or die "rawdeflate failed: $RawDeflateError\n";

   Compressing multiple files
    To compress all files in the directory "/my/home" that match "*.txt" and store the compressed
    data in the same directory

        use strict ;
        use warnings ;
        use IO::Compress::RawDeflate qw(rawdeflate $RawDeflateError) ;

        rawdeflate '</my/home/*.txt>' => '<*.1951>'
            or die "rawdeflate failed: $RawDeflateError\n";

    and if you want to compress each file one at a time, this will do the trick

        use strict ;
        use warnings ;
        use IO::Compress::RawDeflate qw(rawdeflate $RawDeflateError) ;

        for my $input ( glob "/my/home/*.txt" )
        {
            my $output = "$input.1951" ;
            rawdeflate $input => $output
                or die "Error compressing '$input': $RawDeflateError\n";
        }

OO Interface
  Constructor
    The format of the constructor for "IO::Compress::RawDeflate" is shown below

        my $z = IO::Compress::RawDeflate->new( $output [,OPTS] )
            or die "IO::Compress::RawDeflate failed: $RawDeflateError\n";

    It returns an "IO::Compress::RawDeflate" object on success and undef on failure. The variable
    $RawDeflateError will contain an error message on failure.

    If you are running Perl 5.005 or better the object, $z, returned from IO::Compress::RawDeflate
    can be used exactly like an IO::File filehandle. This means that all normal output file
    operations can be carried out with $z. For example, to write to a compressed file/buffer you can
    use either of these forms

        $z->print("hello world\n");
        print $z "hello world\n";

    The mandatory parameter $output is used to control the destination of the compressed data. This
    parameter can take one of these forms.

    A filename
         If the $output parameter is a simple scalar, it is assumed to be a filename. This file will
         be opened for writing and the compressed data will be written to it.

    A filehandle
         If the $output parameter is a filehandle, the compressed data will be written to it. The
         string '-' can be used as an alias for standard output.

    A scalar reference
         If $output is a scalar reference, the compressed data will be stored in $$output.

    If the $output parameter is any other type, "IO::Compress::RawDeflate"::new will return undef.

  Constructor Options
    "OPTS" is any combination of zero or more the following options:

    "AutoClose => 0|1"
         This option is only valid when the $output parameter is a filehandle. If specified, and the
         value is true, it will result in the $output being closed once either the "close" method is
         called or the "IO::Compress::RawDeflate" object is destroyed.

         This parameter defaults to 0.

    "Append => 0|1"
         Opens $output in append mode.

         The behaviour of this option is dependent on the type of $output.

         *    A Buffer

              If $output is a buffer and "Append" is enabled, all compressed data will be append to
              the end of $output. Otherwise $output will be cleared before any data is written to
              it.

         *    A Filename

              If $output is a filename and "Append" is enabled, the file will be opened in append
              mode. Otherwise the contents of the file, if any, will be truncated before any
              compressed data is written to it.

         *    A Filehandle

              If $output is a filehandle, the file pointer will be positioned to the end of the file
              via a call to "seek" before any compressed data is written to it. Otherwise the file
              pointer will not be moved.

         This parameter defaults to 0.

    "Merge => 0|1"
         This option is used to compress input data and append it to an existing compressed data
         stream in $output. The end result is a single compressed data stream stored in $output.

         It is a fatal error to attempt to use this option when $output is not an RFC 1951 data
         stream.

         There are a number of other limitations with the "Merge" option:

         1    This module needs to have been built with zlib 1.2.1 or better to work. A fatal error
              will be thrown if "Merge" is used with an older version of zlib.

         2    If $output is a file or a filehandle, it must be seekable.

         This parameter defaults to 0.

    -Level
         Defines the compression level used by zlib. The value should either be a number between 0
         and 9 (0 means no compression and 9 is maximum compression), or one of the symbolic
         constants defined below.

            Z_NO_COMPRESSION
            Z_BEST_SPEED
            Z_BEST_COMPRESSION
            Z_DEFAULT_COMPRESSION

         The default is Z_DEFAULT_COMPRESSION.

         Note, these constants are not imported by "IO::Compress::RawDeflate" by default.

             use IO::Compress::RawDeflate qw(:strategy);
             use IO::Compress::RawDeflate qw(:constants);
             use IO::Compress::RawDeflate qw(:all);

    -Strategy
         Defines the strategy used to tune the compression. Use one of the symbolic constants
         defined below.

            Z_FILTERED
            Z_HUFFMAN_ONLY
            Z_RLE
            Z_FIXED
            Z_DEFAULT_STRATEGY

         The default is Z_DEFAULT_STRATEGY.

    "Strict => 0|1"
         This is a placeholder option.

  Examples
    TODO

Methods
  print
    Usage is

        $z->print($data)
        print $z $data

    Compresses and outputs the contents of the $data parameter. This has the same behaviour as the
    "print" built-in.

    Returns true if successful.

  printf
    Usage is

        $z->printf($format, $data)
        printf $z $format, $data

    Compresses and outputs the contents of the $data parameter.

    Returns true if successful.

  syswrite
    Usage is

        $z->syswrite $data
        $z->syswrite $data, $length
        $z->syswrite $data, $length, $offset

    Compresses and outputs the contents of the $data parameter.

    Returns the number of uncompressed bytes written, or "undef" if unsuccessful.

  write
    Usage is

        $z->write $data
        $z->write $data, $length
        $z->write $data, $length, $offset

    Compresses and outputs the contents of the $data parameter.

    Returns the number of uncompressed bytes written, or "undef" if unsuccessful.

  flush
    Usage is

        $z->flush;
        $z->flush($flush_type);

    Flushes any pending compressed data to the output file/buffer.

    This method takes an optional parameter, $flush_type, that controls how the flushing will be
    carried out. By default the $flush_type used is "Z_FINISH". Other valid values for $flush_type
    are "Z_NO_FLUSH", "Z_SYNC_FLUSH", "Z_FULL_FLUSH" and "Z_BLOCK". It is strongly recommended that
    you only set the "flush_type" parameter if you fully understand the implications of what it does
    - overuse of "flush" can seriously degrade the level of compression achieved. See the "zlib"
    documentation for details.

    Returns true on success.

  tell
    Usage is

        $z->tell()
        tell $z

    Returns the uncompressed file offset.

  eof
    Usage is

        $z->eof();
        eof($z);

    Returns true if the "close" method has been called.

  seek
        $z->seek($position, $whence);
        seek($z, $position, $whence);

    Provides a sub-set of the "seek" functionality, with the restriction that it is only legal to
    seek forward in the output file/buffer. It is a fatal error to attempt to seek backward.

    Empty parts of the file/buffer will have NULL (0x00) bytes written to them.

    The $whence parameter takes one the usual values, namely SEEK_SET, SEEK_CUR or SEEK_END.

    Returns 1 on success, 0 on failure.

  binmode
    Usage is

        $z->binmode
        binmode $z ;

    This is a noop provided for completeness.

  opened
        $z->opened()

    Returns true if the object currently refers to a opened file/buffer.

  autoflush
        my $prev = $z->autoflush()
        my $prev = $z->autoflush(EXPR)

    If the $z object is associated with a file or a filehandle, this method returns the current
    autoflush setting for the underlying filehandle. If "EXPR" is present, and is non-zero, it will
    enable flushing after every write/print operation.

    If $z is associated with a buffer, this method has no effect and always returns "undef".

    Note that the special variable $| cannot be used to set or retrieve the autoflush setting.

  input_line_number
        $z->input_line_number()
        $z->input_line_number(EXPR)

    This method always returns "undef" when compressing.

  fileno
        $z->fileno()
        fileno($z)

    If the $z object is associated with a file or a filehandle, "fileno" will return the underlying
    file descriptor. Once the "close" method is called "fileno" will return "undef".

    If the $z object is associated with a buffer, this method will return "undef".

  close
        $z->close() ;
        close $z ;

    Flushes any pending compressed data and then closes the output file/buffer.

    For most versions of Perl this method will be automatically invoked if the
    IO::Compress::RawDeflate object is destroyed (either explicitly or by the variable with the
    reference to the object going out of scope). The exceptions are Perl versions 5.005 through
    5.00504 and 5.8.0. In these cases, the "close" method will be called automatically, but not
    until global destruction of all live objects when the program is terminating.

    Therefore, if you want your scripts to be able to run on all versions of Perl, you should call
    "close" explicitly and not rely on automatic closing.

    Returns true on success, otherwise 0.

    If the "AutoClose" option has been enabled when the IO::Compress::RawDeflate object was created,
    and the object is associated with a file, the underlying file will also be closed.

  newStream([OPTS])
    Usage is

        $z->newStream( [OPTS] )

    Closes the current compressed data stream and starts a new one.

    OPTS consists of any of the options that are available when creating the $z object.

    See the "Constructor Options" section for more details.

  deflateParams
    Usage is

        $z->deflateParams

    TODO

Importing
    A number of symbolic constants are required by some methods in "IO::Compress::RawDeflate". None
    are imported by default.

    :all Imports "rawdeflate", $RawDeflateError and all symbolic constants that can be used by
         "IO::Compress::RawDeflate". Same as doing this

             use IO::Compress::RawDeflate qw(rawdeflate $RawDeflateError :constants) ;

    :constants
         Import all symbolic constants. Same as doing this

             use IO::Compress::RawDeflate qw(:flush :level :strategy) ;

    :flush
         These symbolic constants are used by the "flush" method.

             Z_NO_FLUSH
             Z_PARTIAL_FLUSH
             Z_SYNC_FLUSH
             Z_FULL_FLUSH
             Z_FINISH
             Z_BLOCK

    :level
         These symbolic constants are used by the "Level" option in the constructor.

             Z_NO_COMPRESSION
             Z_BEST_SPEED
             Z_BEST_COMPRESSION
             Z_DEFAULT_COMPRESSION

    :strategy
         These symbolic constants are used by the "Strategy" option in the constructor.

             Z_FILTERED
             Z_HUFFMAN_ONLY
             Z_RLE
             Z_FIXED
             Z_DEFAULT_STRATEGY

EXAMPLES
  Apache::GZip Revisited
    See IO::Compress::FAQ

  Working with Net::FTP
    See IO::Compress::FAQ

SUPPORT
    General feedback/questions/bug reports should be sent to
    <https://github.com/pmqs/IO-Compress/issues> (preferred) or
    <https://rt.cpan.org/Public/Dist/Display.html?Name=IO-Compress>.

SEE ALSO
    Compress::Zlib, IO::Compress::Gzip, IO::Uncompress::Gunzip, IO::Compress::Deflate,
    IO::Uncompress::Inflate, IO::Uncompress::RawInflate, IO::Compress::Bzip2,
    IO::Uncompress::Bunzip2, IO::Compress::Lzma, IO::Uncompress::UnLzma, IO::Compress::Xz,
    IO::Uncompress::UnXz, IO::Compress::Lzip, IO::Uncompress::UnLzip, IO::Compress::Lzop,
    IO::Uncompress::UnLzop, IO::Compress::Lzf, IO::Uncompress::UnLzf, IO::Compress::Zstd,
    IO::Uncompress::UnZstd, IO::Uncompress::AnyInflate, IO::Uncompress::AnyUncompress

    IO::Compress::FAQ

    File::GlobMapper, Archive::Zip, Archive::Tar, IO::Zlib

    For RFC 1950, 1951 and 1952 see <http://www.faqs.org/rfcs/rfc1950.html>,
    <http://www.faqs.org/rfcs/rfc1951.html> and <http://www.faqs.org/rfcs/rfc1952.html>

    The *zlib* compression library was written by Jean-loup Gailly "gzip AT prep.edu" and Mark
    Adler "madler AT alumni.edu".

    The primary site for the *zlib* compression library is <http://www.zlib.org>.

    The primary site for gzip is <http://www.gzip.org>.

AUTHOR
    This module was written by Paul Marquess, "pmqs AT cpan.org".

MODIFICATION HISTORY
    See the Changes file.

COPYRIGHT AND LICENSE
    Copyright (c) 2005-2021 Paul Marquess. All rights reserved.

    This program is free software; you can redistribute it and/or modify it under the same terms as
    Perl itself.